1. Field of the Invention
The invention falls within the field of the search for and the mining of oil or gas deposits in which use is made of rotating drill strings consisting of tubular components such as standard and if appropriate heavyweight drillpipes and other tubular elements, in particular drill collars in the region of the bottom hole assembly, connected end-to-end, in accordance with the requirements of the drilling.
The invention relates more particularly to a profiled element for a rotatory drilling outfit, such as a standard or heavyweight pipe or a drill collar, arranged in the body of a rotating drill pipe section.
2. Description of the Related Art
Drill strings of this type can allow in particular directional drilling to be carried out, i.e. drilling, the inclination of which relative to the vertical or the azimuth direction can be varied during the drilling. Directional drilling can nowadays reach depths of the order of 2 to 4 km and horizontal distances of the order of 2 to 14 km.
In the case of directional drilling of this type, comprising practically horizontal runs, the frictional torques due to the rotation of the drill pipe sections in the well can reach very high values over the course of the drilling. The frictional torques can compromise the equipment used or the objectives of the drilling. The frictional torques may thus be such that they make it impossible to continue drilling.
In order to better understand the events which occur at the bottom of the hole, the bottom hole assemblies, close to the drill bit, can be provided with measuring instruments. However, knowledge of the occurrences in the hole remains very patchy.
Pipes have been provided with data transmission systems with an electromagnetic loop at each end of the pipe and a wire connection between the electromagnetic loops in order to retrieve the data provided by the measuring instruments. The wire connection can be provided in the thickness of the wall of the tube forming the central part of the pipe. However, as the wall of the tube is itself as thin as possible for reasons of mass, costs and internal diameter, a longitudinal hole formed in the wall can weaken the tube excessively. Moreover, the machining of a hole of this type is difficult and relatively expensive.
Alternatively, the wire connection can be arranged in the bore of a drillpipe. The wire connection must then be protected against the wear caused by the circulation of the drilling mud inside the pipe or against the deformations resulting from the pressure of the mud or resulting from the axial loading to which the pipe can be subjected (traction, compression, bending). Various solutions have been proposed: a coaxial cable tensioned in the region of its ends, a cable placed between the bore of the drillpipe and a tubular liner pressed against the bore. The applicant has found over the course of its research that these various solutions all had drawbacks, for example that they could significantly reduce the flow section and therefore increase the losses of pressure or else be complex to carry out.